Broadband Ge/SiGe quantum dot photodetector on pseudosubstrate

We report the fabrication and characterization of a ten-period Ge quantum dot photodetector grown on SiGe pseudosubstrate. The detector exhibits tunable photoresponse in both 3- to 5- mu m and 8- to 12- mu m spectral regions with responsivity values up to about 1 mA/W at a bias of -3 V and operates under normal incidence radiation with background limited performance at 100 K. The relative response in the mid- and long-wave atmospheric windows could be controlled through the applied voltage.